KETENES , inchemistry, a
See also:group of organic compounds which may be considered as
See also:internal anhydrides of acetic acid and its substitution derivatives . Two classes may be distinguished: the aldo-ketenes, including ketene itself, together with its mono-alkyl derivatives and
See also:carbon suboxide, and the keto-ketenes which .comprise the dialkyl ketenes . The aldo-ketenes are colourless compounds which are not capable of autoxidation, are polymerized by
See also:pyridine or
See also:quinoline, and are inert towards compounds containing the groupings C:N and C:0 . The ketoketenes are coloured compounds, which undergo autoxidation readily,
See also:form ketene bases on the addition of pyridine and quinoline, and yield addition compounds with substances containing the C:N and C:0 groupings . The ketenes are usually obtained by the
See also:action of
See also:zinc on ethereal or
See also:ethyl acetate solutions of halogen substituted acid chlorides or bromides . They are characterized by their additive reactions: combining with
See also:water to form acids, with alcohols to form
See also:esters, and with
See also:amines to form amides . Ketene, CH2:CO, was discovered by N . T . M . Wilsmore (Jour: Chem .
See also:Soc., 1907, vol . 91, p .
1938) among the gaseous products formed when a platinuth
See also:wire is electrically heated under the
See also:surface of acetic anhydride . It is also obtained by the action of zinc on bromacetyl bromide (H . Staudinger, Ber . 1908, 41, p . 594) . At ordinary temperatures it is a
See also:gas, but it may be condensed to a liquid and finally solidified, the solid melting at -151° C . It is characterized by its penetrating smell . On
See also:standing for some
See also:time a
See also:brown-coloured liquid is obtained, from which a colourless liquid boiling at 126-127 C., has been isolated (Wilsmore, ibid., 1908, 93, p . 946) . Although originally described as acetylketen, it has proved to be a cyclic compound (Ber., 19o9, 42, p . 4908) . It is soluble in water, the solution showing an acid reaction, owing to the formation of aceto-acetic acid, and with alkalis it yields acetates .
It differs from the
See also:simple ketenes in that it is apparently unacted upon by phenols and alcohols . Dimethyl ketene, (
See also:CH3)2C :CO, obtained by the action of zinc on a-brom-isobutyryl bromide, is a yellowish coloured liquid . At ordinary temperatures it rapidly polymerizes (probably to a tetramethylcylobutanedione) . It boils at 34° C . (75o mm.) (Staudinger, Ber . 1905, 38, p . 1735; 1908, 41, p . 2208) .
See also:Oxygen rapidly converts it into a
See also:white explosive solid . Diethyl ketene, (
See also:C2H3)2C :CO, is formed on
See also:heating diethylmalonic an-hydride (Staudinger, ibid.) .
See also:Diphenyl ketene, (C,H6)2C :CO, obtained by the action of zinc on diphenyl-chloracetyl chloride, is an orange-red liquid which boils at 146° C . (12 mm.) .
It does not polymerize .Magnesium phenyl bromide gives triphenyl vinyl
See also:alcohol .
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